ŠMarijuana and
tobacco smoke are chemically similar and have some of the same cancer-causing
and toxic chemicals including: acetaldehyde, ammonia arsenic, benzene, cadmium,
chromium, formaldehyde, hydrogen cyanide, isoprene, lead, mercury, nickel, and quinoline.

ŠMarijuana also
can be contaminated with mold, insecticides or other
chemicals that may be released in secondhand smoke.

What are the
Health Risks?

According
to the Colorado Department of Health and Environment, “Secondhand smoke from
marijuana has many of the same chemicals as smoke from tobacco, including those
linked to lung cancer. While more studies are needed, secondhand smoke from
marijuana may increase the risk of lung cancer. Also, secondhand smoke from marijuana can
cause lung irritation and asthma attacks, and makes respiratory infections more
likely. If you have children or
non-users in your family or home, it is important to practice safer smoking
behaviors, like not smoking indoors or in your car.”

Since
marijuana is illegal by federal law there have been a limited number of studies
examining health risks associated with marijuana use in the United States. Health risks may also be difficult
to determine as marijuana is often used by tobacco users and/or in combination
with tobacco. Some examples of concurrent use are:

ŠMixing marijuana
and tobacco in marijuana papers and in some electronic smoking devices

Recent
studies indicate that exposure to secondhand marijuana smoke may present a public
health hazard.

ŠA 2007 Canadian
government–affiliated study found a number of toxic and cancer-causing
chemicals in secondhand marijuana smoke including three-times the amount of
ammonia in secondhand marijuana smoke than in tobacco smokeas well as other chemicals such
as mercury, cadmium, nickel, lead, chromium, hydrogen cyanide, benzene,
isoprene, toluene, and others.

ŠMarijuana smoke
was added to the list of chemicals known to cause cancer and reproductive
toxicity under the Safe Drinking Water and Toxic Enforcement Act (Proposition
65) in California in 2009 by the California Environmental Protection
Agency.In its report on
marijuana the agency identified at least 33 individual constituents present in
both marijuana smoke and tobacco smoke that are Proposition 65 carcinogens.

ŠA 2014 study of
rats conducted by researchers at the University of California at San Francisco
found substantial impairment of blood-vessel function from 30 minutes of
exposure to secondhand marijuana smoke at levels comparable to those found in
restaurants that allow cigarette smoking.The researchers found that rats exposed to secondhand
marijuana smoke experienced a greater than 50 percent reduction in
flow-mediated dilation, similar to the reduction in artery function seen in
both rats and humans exposed to tobacco smoke in previous studies.The
researchers stated in a press release that because of their similar chemical
composition, “secondhand marijuana smoke and secondhand tobacco smoke are
likely to have similar harmful effects on public health, including
atherosclerosis (partially blocked arteries), heart attack, and stroke.”

ŠOne in six
infants and toddlers admitted to a Colorado hospital with coughing, wheezing,
and other symptoms of bronchiolitis tested positive for marijuana exposure. The
study, "Marijuana Exposure in Children Hospitalized for Bronchiolitis," recruited parents of previously healthy children
between one month of age and two years old who were admitted to Children's
Hospital Colorado (CHC) between January 2013 and April 2014 with bronchiolitis,
an inflammation of the smallest air passages in the lung.

ŠDo electronic
smoking devices (ESDs) with marijuana emit hazardous chemicals? ESDs require certain chemicals for their
operation and are known “to emit ultrafine particles and low levels of toxins that are known to cause cancer.”A 2015
study found that “ESD aerosol particles are smaller than 1000 nanometers, which
is a similar size to tobacco smoke and diesel engine smoke, and bystanders can
be exposed to this aerosol. The exact size distribution depends on the chemical
composition of the electronic cigarette liquid, the e-cigarette device
operation, and user vaping preferences.”

Why Should
Marijuana Smoking be Limited in any Public Place or Workplaces?

ŠEveryone should
have the right to breathe smoke-free air.Smoke-free policies are designed to protect the public and all workers
from the exposure to the hazardous chemicals found in secondhand tobacco smoke.
The same should be true for secondhand marijuana smoke.

ŠFor consistency
and enforcement, smoke-free policies in public places and workplaces should apply
to tobacco and marijuana whether vaped or smoked. Allowing marijuana smoking in
places where smoking is now prohibited could undermine Colorado laws that
protect the public from exposure to secondhand tobacco smoke and pave the way
for the return of tobacco smoking in restaurants, bars, or other work places or
public places. It may violate the section of Amendment 64 that says that
nothing in the law shall “permit consumption that is conducted openly and
publicly or in a manner that endangers others.”Secondhand marijuana smoke or emissions
from electronic smoking devices may endanger the health of others.

ŠVentilation will
not solve the problem. The American Society for Heating, Refrigeration, and Air
Conditioning Engineering (ASHRAE), the organization that develops engineering
standards for building ventilation systems, now bases its ventilation standards
for acceptable indoor air quality on an environment that is completely free
from secondhand tobacco smoke, secondhand marijuana smoke, and emissions from
electronic smoking devices.

ŠSmoke-free
policies provide incentives to quit smoking, and help renormalize smoking
behavior, and are particularly effective among youth and young adults who are
vulnerable to visual cues and social norms of smoking. It is likely that for
marijuana smoke-free policies will have a similar effect.

In the
interest of public health, the exposure to emissions from marijuana smoking or
vaping should be prohibited wherever tobacco smoking is prohibited.

The Group to Alleviate Smoking
Pollution‘s Position on Marijuana
Smoking

The
mission of the Group to Alleviate Smoking Pollution (GASP of Colorado) is to
eliminate secondhand-smoke exposure at work, in public places, and in multiunit
housing through education and policy change. GASP takes no position on
whether marijuana should be legal. Like tobacco, GASP has no objection to
people using marijuana as long as it is done in places where it will not harm
others.Nobody should have to breathe secondhand marijuana smoke against their
will at work, in public, or where they live.

While
the scientific research on the effects of secondhand marijuana smoke is not as
extensive as the research about secondhand tobacco smoke, recent studies
indicate that secondhand marijuana smoke contains some of the same harmful
chemicals as tobacco smoke and may impair blood vessel function.Therefore,
people should avoid exposure to secondhand marijuana smoke and it should not be
allowed in public places, workplaces, and multiunit residential buildings.